Sputtering threshold

The kinetic ion energy flux, (efimax, which is typically 20 W m - [163, 301], will raise the substrate temperature by only a few degrees. Therefore, the influence of ions will be limited to the vicinity of impact. Furthermore, typical ion energies are below the sputtering threshold of silicon [134]. 

The number of atoms sputtered by a single incident ion varies with an ion s individual trajectory. Figure 15 shows the distribution of sputtered particles per incident ion at four different primary energies. As the collision energy increases from 100 to 1000 eV, the most probable yield shifts from 0 to 5 sputtered atoms per ion impact. The computer program, TRIM, mentioned earlier, provides quantitative simulations of both sputtering thresholds and yields. ... 

The sputtering yield, contrary to the sputtering threshold, is clearly dependent on the ion mass especially in the range of the maximum. For example, in the case of gold, for Xe+ ions it is about 3 times higher than with Ar+ ions. 

Potential sputtering thus serves to explain why sputtering can be noted, albeit at extremely low yields, below the kinetic sputtering threshold (the kinetic sputtering threshold is between 15 and 40 eV depending on the system) that scales with the primary ion charge (Malherbe 1994). 

The sputtering threshold energy is a rather vague number that is the lowest energy of the bombarding particle that can cause sputtering. Generally, it is considered that incident particle... 

Sputtering threshold The minimum incident particle energy necessary to cause sputtering. 

An important intermediate range of energies is from the so-called displacement cascade threshold to the sputtering threshold. Displacement cascades occur when a surface atom strikes an atom below, which strikes one below that, etc. until one atom ends up on an interstitial site. This sequence is shown in Figure 11.32. A displacement cascade is the lowest-energy process that results in a real defect in the sohd. Interstitial defects move rapidly. As long as they are close enough to the... 

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